1. Field of the Invention
The present invention relates to methods and apparatuses for gelling liquefied gasses such as liquid propane (LP), liquid methane (LCH4), liquid mixed oxides of nitrogen, (MON-X), or cryogenic liquids such as liquid oxygen (LOX). The apparatus includes a churn mixer specially adapted for liquefied gasses and the associated method produces gelled rocket propellants and other useful gelled liquefied gasses.
2. Description of Related Art
Methods and apparatus for gelling rocket fuels are known in the art. Methods of gelling liquefied gasses and cryogenic liquids can be found in the following patents, which are incorporated by reference. U.S. Pat. No. 4,011,730 discloses crystals of ice or methyl alcohol as gelling agents to gel liquefied natural gas in order to improve transportation efficiency by displacing inert gasses normally dissolved in the fuel. U.S. Pat. No. 4,295,346 discloses a system for gelling cryogenic liquids, including rocket fuels, using crystallized vapor droplets as gellant. U.S. Pat. No. 4,305,256 describes a process for making methane cryogenic liquid gels by forming a mixture of cryogen vapor and droplets and combining the mixture with a gelling agent that is a liquid or gas at ambient temperature but a solid at cryogenic temperatures. U.S. Pat. No. 5,705,771 provides a cryogenic rocket propellant comprising a slurry of solid methane in liquid hydrogen.
The preceding inventions are directed to the large-scale preparation of gelled liquefied gasses or cryogenic liquids. Small rocket motors, such as those used to provide attitude control require fuels of high quality and reliability and in smaller amounts than booster rockets, and other large rocket motors. Apparatus and methods are needed for the production of high quality gelled liquefied gasses with uniform distribution of gellant and particulate dopants and desirable rheological properties. The present invention provides apparatus and methods to satisfy this need and has been demonstrated for the production of gelled liquid propane (GLP) and mixed oxides of nitrogen (MON), including 70% N2O4+30% NO (MON-30). The products are of high quality and made in amounts suitable for rocket motors such as those found in divert and attitude control systems.